Degassing
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chickabeelane
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I degas must in the primary fermentation vessel (in other words, Home Depot plastic pail) in the morning and evening for about the first 5 - 7 days. After I know primary (aerobic) fermentation is complete, I rack into a secondary carboy and leave it alone until the lees drop and the mead clears. My 2 cents. I'm sure others do differently.
fatbloke
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See I know it's semantics, but the primary purpose of early stage agitation is to aerate/introduce O2 for yeast development and not the removal of the carbonic acid/dissolved CO2. Yes it does help prevent foaming eruptions too, but again its not the primary reason is it.....
If you think on it and draw parallels to other home brewing, the beer makers tend not to aerate early stage do they, I'd guess thats because they seem to use technique that gets air/O2 into their wort before pitching and because wort ferments much more easily than honey can. Not forgetting that they're dealing with a lower alcohol product thats much less "protected" and the lower levels of fermentables are much more prone to spoilage than our meads - generally speaking anyway.....
And I pick up on it, not because I want to be petty, but if we are using the same terminology at the correct points, it doesn't matter which version of English we speak, its understood straight away where the poster is.....
Ergo, degassing is done once the fermentation is complete, to remove any dissolved CO2 that may be causing a "tanginess" to the taste of the brew, plus it can also help to clear a batch quicker.
The choice of a lees stirrer of some kind (either one with small plastic arms that extend by the centrifuge action or one with a smallish loop of nylon type plastic string that has a circular whipping type action, both not disturbing the upper part of the liquid to draw a vortex and potentially increasing the surface area etc).
Or indeed, some form of vacuum pump (my preferred method but only suited to glass fermenters), or for smaller batches, capping the fermenter, then agitation, stopping to release any pressure buld up every now and again (generally not for plastic fermenters)....
Actually, for many the purpose of stirring/aerating in primary IS for the removal of c02. C02 is poisonous to yeast, and recent studies and experiments show that a mead is ready much sooner and the yeast is much healthier with degassing in primary!
I think KC touched at that point in her sticky thread "what I learned at the NHC 2010" in this forum.
I think KC touched at that point in her sticky thread "what I learned at the NHC 2010" in this forum.
Just go till it seems when the fermentation is starting to die down and be less active. That is usually when anywhere from 1/3 to 1/2 of the fermentation is complete.
Adding in O2 for healthy yeast is really important but also with meads acid levels are important to keep in check. Dissolved CO2 is Carbonic Acid and releasing a lot of that back into its gas form will help keep the PH from dipping too low. So a lot of great points are made above and there is truth to it all.
Adding in O2 for healthy yeast is really important but also with meads acid levels are important to keep in check. Dissolved CO2 is Carbonic Acid and releasing a lot of that back into its gas form will help keep the PH from dipping too low. So a lot of great points are made above and there is truth to it all.
chickabeelane
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regas? (The O2) and degas (the CO2) for 5 - 7 days, or, like Arpolis said, until vigorous fermentation has stopped. If you don't have a lot of foam when you are stirring you are probably good to go.
fatbloke
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I'm still gonna stick to my "aeration" philosophy.
I don't go with dates and times either - yeast don't wear watches !
As I don't bother checking temperatures, I can't.
I just aerate by either using a stick blender or an electric balloon whisk (sanitised). If there's a cap to punch down, I do that, but I do the aeration, then I measure gravity. I only aerate down to the 1/3rd sugar break before air locking the batch off.
I read around the bazaars a fair bit and some like to aerate/de-gas or whatever you want to consider it as, and some like to do this until the 1/2 sugar break and others to the 2/3rd's sugar break.
Is there any hard and fast rule about this, I don't know. I just follow convention and the suggestion of the 1/3rd point, as perpetuated over at Gotmead.
There have been a few who have access to stir plates. I myself, have looked into that and haven't managed to make a controllable one or come up with enough money to buy a proprietary one, built for lab use that will likely have enough power/strength to stir a gallon batch (I did get a 5 litre Erhlermeyer flask ready to use though). The anecdotal evidence is that using a stir plate to keep the yeast matter in suspension, will continually create the necessary nucleation points for the carbonic acid to attach and come out as gaseous CO2, and this continual removal of the gas will help the fermentation process (one person discussed using it for a show mead, and apparently managed to get it down to just above 1.000 in a few weeks, for a 14% ABV brew - which seems unheard of with show meads, certainly in less than 6 months).
Hence there is likely something in that, but how much is related to aeration and O2 for yeast development, and prevention of build up of dissolved CO2, I can't even begin to suggest.
I do understand that if there's too much O2, then the yeast produce more CO2 and less alcohol, which I believe is likely to be wasted fermentables.
Plus while Yooper asserts that CO2 being injurious to yeast, once the colony is built up to a reasonable level I understood that it's just the increasing levels of alcohol that are of note, as that is where the producers get their tolerance data from (if they actually publish it, and I understand that it's only Lallemand who routinely do that).
Hey ho!, more reading to do, more papers to find etc......
I don't go with dates and times either - yeast don't wear watches !
As I don't bother checking temperatures, I can't.
I just aerate by either using a stick blender or an electric balloon whisk (sanitised). If there's a cap to punch down, I do that, but I do the aeration, then I measure gravity. I only aerate down to the 1/3rd sugar break before air locking the batch off.
I read around the bazaars a fair bit and some like to aerate/de-gas or whatever you want to consider it as, and some like to do this until the 1/2 sugar break and others to the 2/3rd's sugar break.
Is there any hard and fast rule about this, I don't know. I just follow convention and the suggestion of the 1/3rd point, as perpetuated over at Gotmead.
There have been a few who have access to stir plates. I myself, have looked into that and haven't managed to make a controllable one or come up with enough money to buy a proprietary one, built for lab use that will likely have enough power/strength to stir a gallon batch (I did get a 5 litre Erhlermeyer flask ready to use though). The anecdotal evidence is that using a stir plate to keep the yeast matter in suspension, will continually create the necessary nucleation points for the carbonic acid to attach and come out as gaseous CO2, and this continual removal of the gas will help the fermentation process (one person discussed using it for a show mead, and apparently managed to get it down to just above 1.000 in a few weeks, for a 14% ABV brew - which seems unheard of with show meads, certainly in less than 6 months).
Hence there is likely something in that, but how much is related to aeration and O2 for yeast development, and prevention of build up of dissolved CO2, I can't even begin to suggest.
I do understand that if there's too much O2, then the yeast produce more CO2 and less alcohol, which I believe is likely to be wasted fermentables.
Plus while Yooper asserts that CO2 being injurious to yeast, once the colony is built up to a reasonable level I understood that it's just the increasing levels of alcohol that are of note, as that is where the producers get their tolerance data from (if they actually publish it, and I understand that it's only Lallemand who routinely do that).
Hey ho!, more reading to do, more papers to find etc......
I've always thought of degassing and aeration as two different processes. I aerate by using a hand mixer and I run it at the surface and splash the hell out of it. As fermentation continues I do his up to 1/3 sugar break. As fermentation heads toward that 1/3 mark degassing takes place at the same time I'm aerating.
After the 1/3 mark the hand mixer goes deep into the bucket. Blip blip goes the blender. Very short bursts and out comes the CO2. No aeration is taking place because I am not disrupting the surface. Out comes the CO2 and this keeps carbonic acid from building up. I do this several times a day while fermentation is vigorous. Once the CO2 output slows down as the fermentation slows I stop degassing.
After the 1/3 mark the hand mixer goes deep into the bucket. Blip blip goes the blender. Very short bursts and out comes the CO2. No aeration is taking place because I am not disrupting the surface. Out comes the CO2 and this keeps carbonic acid from building up. I do this several times a day while fermentation is vigorous. Once the CO2 output slows down as the fermentation slows I stop degassing.
